CHEMICAL AND BACTERIOLOGICAL EXAMINATION OF SOIL. 



769 



Addendum 



Dr Stewart's Boring Instrument. 



The boring instrument devised by Dr Stewart, and used by me in obtaining the 

 samples of soil from the Arboretum, is an exceedingly ingenious instrument, and by its 

 means reliable samples can readily be obtained. It is made throughout of steel-tubing. 

 The cutting section, specially hardened, and provided at its point with a strong taper 

 screw, has in it a long cutting-slot, one edge of which is sharp, the other being rounded 

 off. This slot can be opened or closed by means of a handle A attached to a rod passing 

 down the interior of the bore to a hollow " plunger " (0 in section). When A is pulled 



e 



up, is elevated and leaves the cutting-slot open. Similarly, when A is pushed down, H 

 (the cutting-slot) is closed. A transverse section of the cutter is shown in F. E is a 

 projection attached to the plunger, which, when the plunger is raised, clears the cutting- 

 slot of any earth got during the sinking of the borer. In using the instrument, having 

 got it down to the required depth, the cutting-slot is opened by pulling up the handle 

 A, boring is resumed, and when it is judged that a sufficiently large sample of soil is 

 contained in the cavity of the cutter, the cutting-slot is closed by pushing down the 

 handle A, and firmly pinching it by means of the thumb-screw B. The borer is now 

 pulled up, and the sample of soil emptied into a suitable vessel. 



